Though manual development, washing and gum application, also referred to as "gumming", is still practiced by the occasional user of photolithographic plates, the large scale commercial utilization of offset plates has made automatic processing of exposed plates an economic necessity. Numerous machines have been proposed to execute otherwise manually performed tasks and have met with qualified success. Machines specifically adapted to process exposed photolithographic plates automatically are disclosed in U.S. Pat. Nos. 3,608,464; 3,593,641; 3,589,261; 3,562,834; 3,448,720; and others.
In general, the more successful machines have emulated the rotary, heretofore manual movement, particularly for the development of the plate. Consequently, it has been popularly believed that failure of other modes of mechanical rubbing motion as a substitute for manual rubbing is a foregone conclusion.
Moreover, the more successful machines are relatively large, enormously complicated and, not unexpectedly, require a capital investment which precludes their acquisition by a small user of plates. With respect to size, it is noted that available machines, for plates from about 25 inches to about 33 inches in width, will not pass, fully assembled, through a standard 36 inches wide doorway and consequently must be assembled at the installation site, preferably by a qualified factory representative. Similarly a factory-trained maintenance person is generally required to diagnose and rectify malfunctions of prior art machines due to the complicated inter-relationship of moving parts and the large number of electrical circuits. Thus, there has been a growing need for a simple, inexpensive automatic plate processor which will not only be easy to acquire but easy to maintain; and which is mechanically as ruggedly as it is photographically, routinely reproducible in results. This invention is directed to such a need.